Rabies vaccines are safe and efficient, say experts

Meghna K

Representational Image: Mathrubhumi

Reports of death following rabies infection, despite vaccination, have spread panic among the public and sparked heated discussions over the efficacy of anti-rabies vaccines available in the state. In the past 6 years, Kerala has recorded a consistent surge in animal attacks, especially dog bites. Compared to the data in the last year, the total figures of death cases touched two times high in 2022, with 21 deaths to date. In conjunction with administering vaccines on time, getting a grasp of what is being injected into the body and how it works is significant in the current circumstance.

All about vaccination schedules

Vaccination is usually administered to prevent the infection of any disease in the future. However, taking jabs of anti-rabies vaccines even after being bitten by rabid animals is effective as the slowly moving virus may take many weeks to metamorphose into fatal encephalitis affecting the central nervous system.

Dr Rakesh TP

Primary care of the wound stands crucial and the wound has to be washed with soap and water as soon as possible, to remove the maximum possible viruses. The guidelines of World Health Organisation recommend 4 doses of vaccine through the intramuscular route on Days 0, 3, 7, and between days 14-28. Alternatively, the vaccine can be administered intradermally (to the skin) in slightly different doses and schedules as per the availability of expertise and transportation issues of the patient. The rabies immunoglobulin (RIG) is additionally administered, if the bite is judged to be severe, and as much of the dose is injected around the bite site, to block the entry of the virus upfront, said Dr Rakesh TP, a senior infectious diseases consultant in the state.

Administering Rabies Immunoglobulin

Rabies Immunoglobulin has to be administered only once before initiating rabies vaccination schedules to provide antibodies immediately until the body generates its own antibodies. It ensures 'passive protection' in previously unvaccinated persons. However, RIG becomes unnecessary if more than 8 days have passed since the first dose of rabies vaccine has already been administered. Humans, horses and modern cell culture technology constitute three variant sources of RIG. Human Rabies Immunoglobulin (HRIG) is produced from human plasma donors, equine rabies immune globulin is developed from vaccinated horses, and monoclonal antibodies (Mabs) against rabies is produced with the aid of modern cell culture technology. Steering clear of animals or humans for vaccination production and the possibility of large-scale manufacture turn out to be the advantage of Mabs over others.

Meanwhile, the rabies vaccines have tissue culture or embryonated egg origin. Human diploid cell vaccine, purified Vero cell rabies vaccine, purified chick-embryo cell vaccine, and purified duck embryo vaccine are the anti-rabies vaccines available in India. All of them have the same efficiency and are available at low cost. In fact, it is available for free at government hospitals.

Steering clear of animals or humans for vaccination production and the possibility of large-scale manufacture turn out to be the advantage of Mabs | Photo: Sivaprasad G

Causes of deaths despite vaccination

Rabies vaccines are very safe and effective in preventing rabies in humans, and failures are extremely rare if proper techniques and dosing are followed in a timely manner. The cause of death may be due to inappropriate or incomplete administration of vaccines, individual health condition of the patient, delay in seeking treatment, improper wound care, unnoticed wounds, lack of vaccine quality and cold chain. However, a heavy dose of the virus through a severe bite on the head and hands might reach the brain before the vaccine starts producing antibodies.

First aid matters a lot

Studies have shown that the virus can reach the brain as quickly with few weeks and as late as eight years (incubation period). The face and hands contain lots of nerve tissue, and when bitten, the probability of the virus entering into a ‘productive replication’; is high, and hence constitutes a high-risk scenario. All wounds should be washed with plenty of soap and water as soon as possible, and medical advice sough regarding vaccination. Since the incubation period can be very long, in selected situations, the vaccine can be administered after a long period of bite. The vaccination fails to work if the virus has already infected the brain. However, most of the people who survived rabies encephalitis had received some doses of vaccine, suggesting some degree of protection.

A woman bitten by stray dog on face in Wayanad | Photo: Mathrubhumi

Pre-exposure vaccination

Pre-exposure prophylaxis is given to professionals like veterinarians or those who come into contact with dogs and cats frequently. It is very effective if antibody levels are measured frequently and booster doses are taken. At present, it is not recommended to the public.

Methodical scrutiny of vaccines

The Assistant Drug Controllers at 6 various zones in the state issue licences for the distributor companies which ensure an uninterrupted supply of vaccines. The licence issuing authorities scrutinise whether the vaccines are distributed within 24 hours after receiving from the manufacturing facilities and safely stored in cold chain systems. All data regarding production, transportation and storage are being inspected regularly and there is no chance of vaccine failure in the state, said PM Jayan, Drugs Controller and Licencing Authority.

Licence issuing authorities scrutinise whether the vaccines are safely stored in cold chain systems | Photo: AFP

A central team was deputed to check the quality of anti-rabies vaccines distributed in Kerala after the public began to raise eyebrows against the efficiency of vaccines available in the state. Following a detailed probe and inspections, the team comprising experts from the National Centre for Disease Control made it crystal clear that the quality and efficacy of vaccines have never been compromised.

(Information furnished by Dr Rakesh TP, Infectious Diseases Consultant)

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